//-------------------------------------------------------------------------
/// <summary>
/// Calculates the present value volatility sensitivity of the Ibor caplet/floorlet.
/// <para>
/// The present value volatility sensitivity of the caplet/floorlet is the sensitivity
/// of the present value to the implied volatility.
/// </para>
/// <para>
/// The sensitivity to the implied volatility is also called vega.
///
/// </para>
/// </summary>
/// <param name="period"> the Ibor caplet/floorlet period </param>
/// <param name="ratesProvider"> the rates provider </param>
/// <param name="volatilities"> the volatilities </param>
/// <returns> the point sensitivity to the volatility </returns>
public virtual PointSensitivityBuilder presentValueSensitivityModelParamsVolatility(IborCapletFloorletPeriod period, RatesProvider ratesProvider, IborCapletFloorletVolatilities volatilities)
{
validate(volatilities);
double expiry = volatilities.relativeTime(period.FixingDateTime);
double strike = period.Strike;
Currency currency = period.Currency;
if (expiry <= 0d)
{ // Option has expired already or at expiry
return(PointSensitivityBuilder.none());
}
double forward = ratesProvider.iborIndexRates(period.Index).rate(period.IborRate.Observation);
double volatility = volatilities.volatility(expiry, strike, forward);
PutCall putCall = period.PutCall;
double df = ratesProvider.discountFactor(currency, period.PaymentDate);
double vega = df * period.YearFraction * volatilities.priceVega(expiry, putCall, strike, forward, volatility);
return(IborCapletFloorletSensitivity.of(volatilities.Name, expiry, strike, forward, currency, vega * period.Notional));
}
